Climate change

Climate change

Photo: Steve Attwood examines all that’s left of the Ashley Rakahuri River during a drought.

We have three choices: mitigation, adaptation, and suffering. We are going to do some of each. The question is what the mix is going to be. The more mitigation we do, the less adaptation will be required and the less suffering there will be.”

– John Holdren, US Office of Science and Technology Policy under the Obama administration

Not a distant problem?

We have included climate change here as a separate threat. We do so only for clarity, to break down the information into more manageable segments relevent specifically to braided rivers and their ecosystems.

In reality, climate change is a complex, broad-reaching human-induced threat that multiplies all existing threats while creating new and unexpected ones.

For this reason, climate change is often referred to as a ‘risk multiplier’. For example, changing weather patterns are leading to more beech masts, which in turn leads to a population explosion of rats, mice, and stoats.

Climate change also is creating new and unexpected threats. For example, braided river birds like wrybills migrate to the Firth of Thames estuary for winter. That estuary and many others are threatened by rising sea levels. Black-fronted terns also migrate to the coast for winter, flying out to sea to feed on fish, but ocean acidification and changes in oceanic currents already are threatening the oceanic food web. Disease is also a new threat as pathogens once killed by cold weather now spread into new warming areas.

Examples of both new (white) and existing (light grey) threats, and their relationship to direct and indirect impacts (Christie, 2014)

Regardless of what we do to mitigate greenhouse gas emissions, the climate will continue to change and become more challenging into the indefinite future. The goals now are twofold: reduce the weight of those impacts (mitigation) and find ways to cope with what’s coming (adaptation).

The recent IPCC (Intergovernmental Panel on Climate Change) report (October 2018) makes it very clear that if we do not mitigate the impacts, the consequences will be profound, making adaptation extremely difficult and suffering more profound. This is supported by a recent report from the London School of Economics: existing economic risks are vastly underestimated.

There is good news!

Braided river ecosystems evolved to thrive in response to rapid and dynamic change.

Of all the ecosystems in New Zealand, braided rivers are the most inherently capable of resiliency to climate change. But only if we protect and restore them so that they can continue to support our unique birds and wildlife and provide priceless and irreplacable ecosystem services at a time when we most need them.

References and research material